However, the pitchers listed above are all talented and should be able to find a home before too long. Darvish is expected to get a big deal (at some point), but the market for Arrieta is perhaps more interesting. His 2017 season was an odd one, starting off terribly then becoming terrific as the year went on -- according to the baseball card numbers, at least.

What should teams expect from him over the next few years? Would teams be crazy to offer anything more than a four-year deal for a starter going into his age-32 campaign? Can he provide what Jon Lester gave to the Chicago Cubs when he arrived as a free agent a few years ago, or does Arrieta pose a riskier proposition?

A Tale Of Two Halves

In 101.1 innings prior to the All-Star break, Arrieta posted an ERA of 4.35 and gave up a slash line of .247/.320/.422, a weighted on base average (wOBA) of .318, a fielding independent pitching (FIP) of 4.18 and an expected fielding independent pitching (xFIP) of 3.99. His second half was much better, albeit in a smaller sample size. He pitched 67.0 innings and had a 2.28 ERA, allowing a slash line of .213/.280/.394 with a .288 wOBA allowed, a FIP of 4.11 and an xFIP of 4.30.

But what caused an improvement in those figures? The chart below shows there wasn't a lot of difference in his peripherals.

Split

Strikeout Rate

Walk Rate

Homers per Nine

BABIP

Strand Rate

First Half

23.5%

8.1%

1.24

.300

67.0

Second Half

22.4%

7.4%

1.21

.246

83.6

Arrieta's strikeout rate actually went down a bit in the second half, although he reduced his walk rate, as well. He didn't see his home run rate go down, either.

The key factors seems to be a lower BABIP and a higher strand rate. In the first half, his .300 BABIP was only a scant bit higher than the league average (.298), which indicates he wasn't particularly unlucky. When it fell to .246 in the second half, that indicates he got much luckier after the All-Star Break. That lower BABIP also affected the rate at which he left runners on base, and his 83.6% second-half strand rate is a number that is probably not sustainable considering the MLB season-long average last year was 72.6%.

And it's not like Arrieta's low BABIP was due to him giving up fewer hard-hit balls. His first-half hard-hit rate of 29.2% is actually better than his second-half hard-hit rate of 29.8%.

So was his second half really all that much better than his first half? It doesn't appear so.

Lackluster Splits

Back in 2015, when Arrieta won the National League Cy Young Award by going 22-6 with a 1.77 ERA in 229 innings, he held left-handed hitters to an incredibly low .158 batting average with a .221 on-base percentage and a slugging percentage of .228. He was very effective against lefties in 2016, as well, giving up a slash line of .193/.308/.304 to opposite-handed hitters.

Last year was a different story.

Left-handed hitters slashed .266/.345/.498 against him over 325 total lefties faced, a dramatic increase across the board. Right-handers hit .207/.270/.340. The problem was his cutter, which was among the most effective in baseball in 2015, saving 23.5 runs above average overall. Last year, that pitch cost his team 9.7 runs above average.

For Arrieta, the cutter has been an important weapon against left-handers throughout his career, but it was not as effective a pitch for him in 2017.

Breaking Preconceived Notions

It's easy to remember Arrieta as the unconsciously dialed-in dude who had one of the greatest seasons in MLB history three years ago, but the table below shows he's not that guy anymore. Here's his 2017 production alongside the other starters who ranked right near him in Wins Above Replacement, per FanGraphs.

Mileage

Arrieta will be 32 years old next year, and he registered his lowest innings total (168.1) since 2014 (156.2), all while making five more starts. He's not pitching as deep into games, and his velocity has dropped -- from an average heater of 94.9 miles per hour in 2015 to 92.6 miles per hour last year. In 2015, he piled on 19.2 postseason innings on top of the 229 he threw in the regular season (248.2 total), and in 2016, Arrieta threw a combined 219.2 innings (regular and postseason).

That seems like an overpay when Cobb is still on the market and can probably be had for less. But for teams with a window for postseason contention in 2018 and 2019, overpaying for Arrieta now on the chance he returns to his output of 2015 and 2016 may be worth it in the short-term.